Method of controlling warning lights to enter low power mode includes steps of: setting predetermined ID Number of warning lights as starter, and remaining ID numbers as receivers; warning light set as starter receiving start command from control bus through signal line, and sending data, clock pulse, and ID information from data bus, and choosing low power mode to flash; warning lights set as receivers obtaining data, clock pulse, and ID information from data bus through signal lines, and flash mode of receivers and starter flashing in low power mode, and active switch of control circuit that executes low power mode receiving low power command sent from starter and forming conductive state, and current-reducing resistor which is electrically connected to active switch reducing passing current to predetermined ratio, so that reduced current is transmitted to receivers and then starter executes low power mode and reduces brightness of warning lights.

Method of controlling warning lights to enter low power mode includes steps of: setting predetermined ID Number of warning lights as starter, and remaining ID numbers as receivers; warning light set as starter receiving start command from control bus through signal line, and sending data, clock pulse, and ID information from data bus, and choosing low power mode to flash; warning lights set as receivers obtaining data, clock pulse, and ID information from data bus through signal lines, and flash mode of receivers and starter flashing in low power mode, and active switch of control circuit that executes low power mode receiving low power command sent from starter and forming conductive state, and current-reducing resistor which is electrically connected to active switch reducing passing current to predetermined ratio, so that reduced current is transmitted to receivers and then starter executes low power mode and reduces brightness of warning lights.

The present application relates to an LED system with controllable power supply and control method and device thereof. The control method comprises: detecting output port voltages of a main driving module, and when a number of ports whose voltage is less than a first preset voltage or a number of ports whose voltage is greater than a second preset voltage exceeds a first preset value, coarsely adjusting the power supply; determining by each of cascaded slave driving modules an adjustment strategy according to its own output port voltages and an adjustment strategy from a subsequent slave driving module, and sending its adjustment strategy to a previous slave driving module; determining by the main driving module an adjustment strategy of the power supply according to the adjustment strategy from the slave driving module and the output port voltages of the main driving module, and fine-adjusting the power supply.

The present disclosure provides a light emitting element driving device. The light emitting element driving device includes a constant current circuit and a current detection unit. The constant current circuit includes: a first transistor including a first end, a second end and a control end connected to an external terminal; a current setting resistance connected to the second end of the first transistor; and a drive amplifier including a first input end connected to a first node to which the first transistor and the current setting resistance are connected, a second input end to which a current set voltage is applied, and an output end connected to the control end of the first transistor. The current detection unit generates a current detection signal based on a feedback voltage generated in the first node.

A lighting circuit turns on a plurality of semiconductor light sources. Multiple current sources are each coupled to a corresponding semiconductor light source. A switching converter supplies a driving voltage V.sub.OUT across each of multiple series connection circuits each formed of the semiconductor light source and the current source. A converter controller employing a ripple control method turns on a switching transistor of the switching converter in response to a voltage across any one of the multiple current sources decreasing to a bottom limit voltage.

A minimum voltage detector circuit is disclosed. The circuit includes a plurality of LED strings each having a plurality of series-coupled LEDs. The minimum voltage detector circuit is configured to detect a minimum voltage from among the plurality of LED strings, and also to perform open/short detection among the plurality of LED strings. The minimum voltage detector circuit includes a plurality of voltage comparators and correspondingly coupled replica circuits. Each of the voltage comparators includes an amplifier having a first input coupled to a cathode of a last LED of one of the plurality of LED strings, an output, and a second input coupled to the output. Each voltage comparator further includes a replica circuit coupled to the amplifier. The replica circuit is configured to maintain an output transistor of the amplifier in an active state when the amplifier is in an unbalanced state.

A voltage-regulating drive circuit for an LED luminaire is disclosed. The drive circuit includes one or several series of LED light engines. A voltage source with a regulator is connected to the series of LED light engines to forward-bias the light engines. The circuit also includes a driver integrated circuit, which may drive the series of LED light engines using, e.g., pulse-width modulation (PWM). The circuit also includes a feedback circuit connected to the cathode end of the series of LED light engines. The feedback circuit receives a remainder voltage and creates a feedback output signal that upregulates or downregulates the regulator of the voltage source to keep a minimum operating voltage on the driver integrated circuit and to compensate for variations in forward voltages among LED light engines in the series.

The present disclosure provides a driving circuit, configured to couple to a light emitting diode (LED) and a power supply circuit. The driving circuit includes a comparator, a serial input interface, and an integrating unit. The comparator is configured to couple to the LED and determine whether a cathode voltage of the LED is lower than a threshold value and generate a monitoring data. The serial input interface is configured to receive a serial input data from a previous driving circuit. The integrating unit is coupled to the comparator and the serial input interface and configured to integrate the monitoring data and the serial input data to generate an output data. The output data is transmitted to a following driving circuit or feedbacked to the power supply circuit in order to modulate a power voltage that the power circuit provides to the LED.

A lighting unit includes a power supply that provides a maximum voltage and multiple LED lighting circuits. Each of the LED lighting circuits includes an LED string, multiple switches, a switching sequencer and a switch controller. The LED string includes multiple series-connected emitters having a total forward voltage that exceeds the maximum voltage of the power supply. Each of the switches is coupled in parallel with a respective LED of the LED string. The switching sequencer provides a sequence of switching patterns such that a total forward voltage of simultaneously active LEDs in each switching pattern does not exceed the maximum voltage of the power supply. The switch controller actuates switches according to each of the switching patterns in the sequence. The LED string of each of the plurality of LED lighting circuits is arranged in a two-dimensional array.

Aspects of the subject technology relate to electronic devices having a display. The display includes a channel of light emitting diodes (LEDs) having controllable brightness levels and control circuitry coupled to the channel of LEDs. The control circuitry provides a pulse width modulated (PWM) signal having a duty cycle to control the brightness levels. An adaptive headroom control circuitry is configured to sense a headroom voltage signal for the channel of LEDs and apply a first time period for blanking the headroom voltage signal during the first time period that is associated with a settling time for the headroom voltage signal.